The present invention relates generally to foams that are used to fill cavities, cracks, and crevices to enhance the sealing and insulating properties of buildings and, more particularly, to a foam that is contained within an enclosed envelope, such as a bag, that can conform to the large volume to be sealed.
Spray foams have found widespread utility in the fields of insulation and structural reinforcement. For example, spray foams are commonly used to insulate or impart structural strength to items such as automobiles, hot tubs, refrigerators, boats, and building structures. In addition, spray foams are used in applications such as cushioning for furniture and bedding, padding for underlying carpets, acoustic materials, textile laminates, and energy absorbing materials. Spray foams are also used as insulators or sealants for home walls.
Two main classes of spray foams are well characterized: polyurethane (non-aqueous) and latex (aqueous). Typically, polyurethane spray foams are formed from two separate components, commonly referred to as an “A” side and a “B” side, that react when they come into contact with each other. The first component, or the “A” side, contains an isocyanate such as a di- or poly-isocyanate that has a high percent of NCO (nitrogen, carbon and oxygen) functional groups on the molecule. The second component, or “B” side, contains nucleophilic reagents such as polyols that include two or more hydroxyl groups, silicone-based surfactants, blowing agents, catalysts, and/or other auxiliary agents. The nucleophilic reagents are generally polyols, primary and secondary polyamines, and/or water. Preferably, mixtures of diols and triols are used to achieve the desired foaming properties. The overall polyol hydroxyl number is designed to achieve a 1:1 ratio of first component to second component (A:B).
U.S. Pat. No. 5,444,099 to Abe et al., U.S. Pat. No. 4,945,120 to Kopp et al. and U.S. Pat. No. 3,984,360 to Galbreath et al. disclose polyurethane spray foams which may be capable of being applied at low temperatures. The polyurethane foams in each these patents require a polyisocyanate component.
Polyurethane foams exhibit a number of problems when sprayed into cavities or crevices. First, they contain high levels of isocyanates, such as methylene-diphenyl-di-isocyanate (MDI) monomers which form droplets that may be inhaled by workers installing the foam if stringent safety precautions are not followed. Even a brief exposure to isocyanate monomers may cause difficulty in breathing, skin irritation, blistering and/or irritation to the nose, throat, and lungs; and extended exposure can lead to serious sequelae, including asthmatic-like reactions and possibly death. Secondly, the residual polymeric methylene-diphenyl-di-isocyanate (PMDI) that is not used has an NCO of about 20% and is considered to be a hazardous waste that can remain in a liquid state in the environment for years. Therefore, specific procedures must be followed to ensure that the PMDI waste product is properly and safely disposed of in a licensed land fill. Such precautions are both costly and time consuming.
In this regard, attempts have been made to reduce or eliminate the presence of isocyanate in spray foams and/or reduce or eliminate isocyanate emissions by spray foams into the atmosphere via the use of latex-based spray foams. Some examples of such attempts are set forth below.
U.S. Patent Publication Nos. 2008/0161430; 2008/0161431; 2008/0161433; 2008/0161432; 2009/0111902; and 2010/0175810 to Korwin-Edson et al. disclose a room temperature crosslinked latex foam, such as for filling cavities and crevices. The foam contains an A-side or component that includes a functionalized latex and a B-side or component that contains a crosslinking agent, and optionally, a non-reactive resin (e.g., a non-functionalized latex). Either or both the A-side or the B-side may contain a blowing agent package. Alternatively, the A-side and the B-side may each contain a component such as an acid and a base that together form a blowing agent package. A plasticizer, a surfactant, a thickener, and/or a co-solvent may optionally be included in either the A- and/or B-side.
U.S. Patent Publication No. 2006/0047010 to O'Leary teaches a spray polyurethane foam that is formed by reacting an isocyanate prepolymer composition with an isocyanate reactive composition that is encapsulated in a long-chain, inert polymer composition. The isocyanate prepolymer composition contains less than about 1 wt % free isocyanate monomers, a blowing agent, and a surfactant. The isocyanate reactive composition contains a polyol or a mixture of polyols that will react with the isocyanate groups and a catalyst. During application, the spray gun heats the polymer matrix, which releases the polyols and catalyst from the encapsulating material. The polyols subsequently react with the isocyanate prepolymer to form a polyurethane foam.
Such spray foams are excellent at sealing smaller cracks, joints and crevices, but generally do not possess sufficient structure to fill large volumes, such as the gap between floor joists where they intersect a wall dividing conditioned and unconditioned spaces, or the large gaps formed where a chimney passes through a floor joist or the large gaps found in furnace flue chases, for example. Although these spaces may be insulated with fibrous insulation, this is generally not sufficient to “seal” the area to prevent air drafts from infiltrating and passing from unconditioned areas to conditioned areas.